The Countryside Restoration Trust has spent several years trapping Mink out of the rivers around Lark Rise Farm, in an effort to eradicate this American invader and to reverse the decline of the Water Vole, which are severely impacted by mink predation. We use Game and Wildlife Conservation Trust mink rafts which float in the river, and have a tunnel that attract Mink to enter where there is a clay base to reveal footprints, or a trap set to catch Mink. In the spring, Mink travel miles looking for mates, especially now that there are so few mink in the area following our efforts, so one or two traps are left at strategic locations with remote detection devices (Mink Police Units) which alert us to the trap being triggered.
On Monday 23rd March 2015 one of the traps in the Shepreth area sent a message and I duly went out first thing to deal with the capture. I was astonished to discover an Otter had managed to get into the trap! Over the years, we have caught more than 150 mink but very few other species – a couple of Polecats, Stoats, Squirrels and Rats, and once, most bizarrely, a Robin – but having talked to dozens of mink trappers across the whole of East Anglia, no-one has ever seen an Otter in one of the traps. The traps are designed with extra small entrances that are supposed to exclude Otters – they are much larger than Mink – but this was clearly a youngster which had somehow left its holt early. Maybe the Otter family had been travelling overnight and this curious individual explored the mink raft.
This gave me the problem of how to get it back out alive! The door can only be opened by moving the locking bar from inside, which means getting into the trap with an Otter. I managed this bit with a metal bar, then used a stick to push the door open from the outside – the stick got a good chomp from the Otter but also made the exit hole even smaller, and it was reluctant to go past, so I tried to hold it open by hand, with the inevitable bite to the finger tip as a parting gift from my accidental inmate. It then shot off through the undergrowth and to find a nice resting place for the day. Luckily I always wear thick leather gloves when dealing with trapped animals, and despite a bit of a crushing sensation there was no blood loss. When I looked at the trap, it was totally vandalised, with the springs and other bits of internal metalwork chewed through. Despite being the first live Otter I’ve seen in Cambridgeshire, I really hope I never get another one!
We know that Otters visit mink rafts all the time, because they leave their tell-tale droppings, called spraints, on top of the tunnels, and we have used infra-red camera traps to reveal their nocturnal visits from time to time. Occasionally a small Otter will enter the tunnel and leave footprints on the clay, but usually they just use the top of the raft.
Otters communicate by smell and hopefully this one will be re-united with its family very soon. There was a nice large spraint close to the raft, and a freshly killed crayfish in the water nearby, so it is likely that the mother will be coming back to look for her youngster as soon as it goes dark. It was clearly in very good health and capable of looking after itself if it came into a conflict with any other species. The Otter comeback has been one of the great conservation success stories of recent times, and they are present throughout the country now, with every river in Cambridgeshire having good levels of occupancy. As they get more and more abundant, they are bound to reveal new behaviour and activities such as this.